Crafty, developed by Robert Hyatt, is a descendant of the Cray Blitz chess engine that was the World Computer Chess Champion from 1983 to 1989.

to install
#apt-get install crafty xboard

start the game with
$xboard -fcb 'crafty' -fd crafty_directory

book off — This options disables the use of opening book for crafty.
ponder off – Crafty can’t think while you are playing your move.
st 1 — Make the maximum thinking time for Crafty just one second.
sd n — Crafty won’t think more than n moves ahead.
If you are able to beat crafty too often, you can also make it more stronger with these options:
hash nK — Makes the hash table bigger
hashp n — Makes the hash table for pawns as large as possible